Apparatus for making pressed wood fiber products



Feb W 1932.' P. G. VON HILDEBRANDT L845 533 APPARATUS FOR MAKING PRESSED WOOD FIBER PRODUCTS Filed NOV. 20, 1928 INVENTOR WDTNESSES Patented Feb. 16, 1932 UNITED STATES PATENT oFElcE PAUL G. VON HILDEBRANDT, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO HOWARD i B. SALKELD, O F PITTSBURGH, PENNSYLVANIA APPARATUS FOR MAKING PRESSED WOOD FIBER PRODUCTS I Application :tiled November 20, 1928. Serial No. 320,604.

`The invention relates to apparatus for press forming boards and similar 'articles from ber, especially from cellulose Y ber, and thechief object is to provide simple and effective apparatus for use in connection with a process of forming highly porous ber articles which is disclosed and claimed in my copending application, Serial No. 320,603 led November 20, 1928.

The process referred to comprises suspending ber free from binder of any kind in an inert medium, such as water, in a cold closed die, and while thus suspended, expressing the major portion of the suspending medium and compacting the ber to form aboard of the desired thickness. In thepreferred practicel of that invention, air is injected into the die prior to the pressing operation. Chemically prepared wood ber is preferably used, and, most suitably, pure cellulose ber produced in accordance with another copending appli cation, Serial No. 320,601, led by me November 20, 1928. The bration process referred to comprises incipiently attacking the cell incrustants and opening the grain of thewood, preferably by digestion with milk of lime, and then compacting the wood under mechanical pressure and removing the balance of' the incrustants by digestion, preferably with caustic soda. A

The ber produced in this manner is soft and strong, and the major portion of the bers retain their natural length. This ber is particularly adapted for use in forming pressed articles by the forming process hereinbefore referred to. Using that ber and process, there is obtained after'dry'mg, a highly porous, coherent product which possesses superior sound and heat insulating properties, and which is produced wholly without binder of any nature. The product is strong and stiff, is grainless andof substantially uniform density throughout and it is not subject to deterioration. y

This invention may be described in connection with the accompanying drawings, in which Fig. 1 is a front elevation of a press embodying the invention; Fig. 2 a horizontal section through the die taken on line II-II, a

Fig. l; and Fig. 3 is a vertical section through the die, taken on line III-III, Fig. 2.

vAccording to this invention, the apparatus comprises a die member provided with a pressing chamber for holding the ber suspension and in which the pressed article is formed. The die is provided `with means for preventing the suspending mediumfrom escaping prematurely, and thismeans preferably comprises pressure-responsive valves effective only upon production of a predetermined pressure in the pressingl operation. Means are also provided for introducing air into the chamber. A ram or pressing platen cooperates with the die chamber for compacting its contents, and preferably this member makes a fluid tight t with the walls of the chamber. These members are mounted -and actuated in any desired manner.

Having reference now to the preferred embodiment shown in the drawings, Fig. 1

`shows a press of a form commonly used in various arts. It comprises a Xed stationary base 1, a head 2,' carried by posts 3 secured to the base, and a vertically movable table 4. The table is guided by the posts 3 and is reciprocated with respect to the head by hydraulic or other means, not shown. Carried by the table and also guided bythe posts, is a die member indicated generally by the numeral 5.

The die shown comprises a box-like pressing chamber 6 bounded by inner walls 7 integral with the base 8. An annular conduit 9 surrounds the outside of chamber 6, this' conduit being preferably formed betweenrthe inner walls7 and outer walls 10, integral with base 8, and closed at the top by a web 11,

as shown in Fig. 3. The inner walls are provided with a plurality of openings 12, which connect the chamber 6 and conduit 9, and small enough to prevent passage of ber therethrough. A screen mayalso be disposed on' the conduit side of walls '7, for the purpose of preventing passage of ber into the conduit, as will be understood in the art.

In the practice of the invention disclosed in my application Serial No. 320, 603, it is preferred to form the ber suspension in the die.

To that end the die is provided with means for introducing suspending medium, as well as with the air connection and pressure-responsive outlet valves previously referred to. For simplicityr of construction these three elements are combined in the manner shown in Fig. 3. TheV outer walls 10 of the die are tapped and threaded to receive a plurality of nipples 13, spaced symmetrically around the die for a purpose hereinafter set forth. A cross or other suitable four-way connection 14 is connected to the outer end of each nipple, and one side opening of each is connected to a water supply line 15, and the other side to a compressed airline 16'. Theselines are suitably valved. A one-way valve connection 17 is made at the other arm ofthe cross to a drain line,y 18. Valve 17 is preferably of the spring-impelled type, which is effective only when the pressure exceeds a predetermined value.

It is essential in the forming process referred to that the fiber be uniformly suspended or floated ink the suspending medium, and also that the medium be expressed uniformly from all sides of the'die. This is in part achieved by the foraminous natureof the chamber walls, and by the use of the regularly spaced inlet and outlet valves. In order to further secure this uniformity of suspending action, baffles 19 are formed in the conduit on walls 7 opposite the nipples.' Water, air or other Huid entering the conduit impinges on these baflies and is diverted uniformly toward each side, so that it enters the die at substantially the same rate at all points.

The pressing action is produced by a platen 2O carried byhead 2. This platen cooperates with the die chamber to express the suspending medium and compact the fiber. Preferably it makes a' sliding it with the walls of chamber 6 so as to form a 'Huid-tight. joint therewith.

In the use of'this press, moist fiber, containing about 25 per cent of water, is placed in chamber 6, and the table is raised to bring platen 2O into and close the chamber. A suitable liquid medium, preferably Water, is then introduced in chamber 6, from line 15, to float the fiber in an excess thereof. After the chamber has been partly filled with the suspension thus formed, the liquid is cut of,and air forced in from line 16 to form a blanket of air under pressure in the space above the suspension. When the air pressure has become equalized, line 16` is closed. The valves 17 are selected so that th'e pressure in the chamber and conduit is insufficient to force them open.

The table-'actuating mechanism is now operated to progressively force the platen farther into the die or pressing chamber, and the first action is to increase the pressure of the air lying over the ber suspension. The p ressure gradually increasing, becomes suiicient to force valves 17 open, and water and air are expressed from the chamber. At the same time, the fibers are compacted, and the pressing action is continued until a board of the desired thickness is obtained. It is preferred formed are light, strong, and highly porous,

their porosity conferring thermal and sound insulating properties superior to the insulators now commonly used. The boards contain no binder of any kind, but they are highly coherent, the ber being mechanically entangled in a satisfactory structure-retaining fashion. These boards also are of substantially uniform density throughout.

It will be understood that the invention is Vnot limited to the production of flat board of the type described, but that other articles possessing the desirable characteristics described for the boards may also be produced. Also, it is not essential that the die move to- Ward a fixed platen, as the reverse operation is equally satisfactory.

I claim: p

1. In -a press for makmg fiber board and the like, the combination of a die member comprising a pressing chamber, an annular conduit surrounding said chamber, a plurality of fluid connections between said chamber and conduit, and a plurality of fluidpressure responsive fluid outlets disposed in said conduit for drainage of said conduit and chamber, a platen member cooperating in fluid-tight relationship with said pressing chamber, and means actuating one of said members with respect to the other member.

' 2, A press for making fiber board and the like, comprising the combination of a die member comprising a pressing chamber bounded by perforated Walls, an annular conduit surrounding said walls, and one-way discharge valves in said conduit, said valves beingactuated by fluid pressure within'the pressing chamber, a platen member cooperating with said pressing chamber and adapted to make fluid-tight fit therewith, and means for actuating one of said members with respect to the other member.

3. A press for making fiber board and the like, comprising the combination of a frame, a table mounted for vertical reciprocation in said frame, a die comprising a pressing chamber formed-between a base and perforated vertical Walls, an annular conduit surrounding said chamber, Huid inlets connected to said conduit, and pressure-responsive one-Way discharge valves connected to said conduit, and a platen adapted to make 'a uid-tight joint with said pressing chamber carried by the frame /for cooperating with theycham er.

42A press for making fiber'board and the like, comprising the combination of a frame, a table mounted for vertical reciprocation in said frame, a die comprising a pressing chamber formed between a base and perforated vertical walls, an annular conduit surrounding said chamber, means for separately introducing water and air into said conduit, and a plurality of one-way uid discharge valves eective only at a predetermined pressure disposed symmetrically about said conduit, and a press platen adapted to move in said chamber and form a uid tight t therewith mounted thereabove. y

5. A press for making ber board and the like comprising a die member having a pressing chamber adapted to receive a charge of ber and provided with means to introduce suspending Huid to uniformly distribute the ber in said chamber, a plurality of normally closed fluid pressure-responsive outlets associated with said chamber for drainage of said fluid, said outlets being opened for drainage of said fluid by application of a predetermined pressure to the fluid, a platen member cooperating in fluid-tight relationship with said chamber, andfmeans actuating one of said members to reciprocate it with respect to the other member.

6. A press for making`ber board and the like comprising the combinationof a die comprising a pressing chamber formed between a base wall member and vertical side wall members integral with the base member, i

a conduit externally associated with one of said members, uid inlets to said conduit, and pressure-responsive discharge valves connected to said conduit, the wall common to said conduit and chamber being perforated, a platen adapted to makev a {luid-tight joint with said pressing chamber, and means actuating thel die with respect to the platen. In testimony whereof, I hereunto sign my name.

PAUL G. voN HILDEBRANDT. 

